How to install heated towel rails according to SANS 10142-1

May 25th, 2018, Published in Articles: Vector

Chris Koen

Electrical contractors frequently want to know how a heated towel rail should be installed in bathrooms and how this is connected to the fixed electrical wiring of the installation.

To ensure a compliant installation of heated towel rails, reference must be made to the national Wiring Code, SANS 10142-1: 2017 (Edition 2).

Clause 7, “Special installations or locations”, states:

7.1 Bathrooms, showers and spas

NOTE: The particular requirements of this sub clause apply to bathtubs, shower basins and the surrounding zones where the risk of shock is increased by a reduction in body resistance and contact of the body with earth potential.

Sub clause 7.1.1.3 makes reference to Table 7.1, and states that “NO electrical equipment shall be installed in ZONE 0 except in accordance sub clause 7.1.3.2 (See also 7.1.4.4)”.

When we look at sub clause 7.1.3.2, which deals with “Protection against electric shock”, we see:

7.1.3.2.1 In zone 0, only protection by safety extra low voltage (SELV) at nominal voltage not exceeding 12 V is permitted, the safety source being installed outside zone 0.

An example of “the safety source” would be an isolating transformer.

Sub clause 7.1.4.4. “Other fixed equipment and heated towel rails” deals with other fixed equipment such as heated towel rails and, in 7.1.4.4.1, we read that this equipment, unless fed from a SELV source, is not permitted in zone 0 and that, in zones 1 and 2, “only equipment as indicated in table 7.1 may be installed”.

Table 7.1 – Conditions under which electrical equipment may be installed in a bathroom

This table lists conditions under which electrical equipment may be installed in a bathroom.

Heated towel rails, which are seen as a “fixed appliance” in zone 1, are allowed under certain conditions: A “denotes that an earth leakage protection shall be provided” and B1 “denotes that the equipment shall be so enclosed in insulating material that it is not possible to touch current-carrying parts with a standard test finger”.

B2 denotes that a “class II appliance shall be used”.

The same applies for zone 2 and, for zone 3, normal provisions of SANS 10142-1 2017 apply.

Table 7.1 and all the figures 7.1.1; 7.1.2; 7.1.3 and 7.1.4 illustrate the zones in the various bathrooms.

Clause 6.16 – Fixed appliances

This clause deals with installation requirements of fixed appliances and the power source to these appliances. The regulations in clause 6.16 state in clause 6.16.1.1 that “fixed appliances do not form part of the electrical installation other than their positioning in relation to the supply and the wiring carried out between different parts of the appliances”.

To find out how power is supplied to heated towel rails, we refer to:

6.16.1.2 – The power supply to every fixed appliance, except luminaires, shall be supplied through

1. a) a disconnecting device that disconnects both live conductors in single-phase supply and all phase conductors in a multiphase supply, or

2. b) a socket-outlet that is directly accessible at all times that any person is exposed to such appliance while the supply is on. In the case of a remotely installed appliance, the position of the disconnecting device shall be indicated by means of a notice in close proximity to or on the appliance.

Refer to the zones in Table 7.1 for the requirements and where such a socket outlet could be installed.

6.16.1.4 – The disconnecting device shall be positioned

1. a) within 1,5 m from the appliance, or

2. b) in a distribution board (if the switch-disconnector is capable of being locked in the open position).

Note that, even where a disconnecting device is on the heated towel rail, a separate disconnecting device shall be provided in the fixed installation to allow for the total removal the appliance. A standard switch is not a switch-disconnector.

6.16.1.5 – A socket-outlet shall supply only one fixed appliance…

If a flexible cord supplies the appliances, you could use a socket-outlet as explained here, but this sub-clause states that it is not recommended that the flexible cable exceeds 3 m. This is to ensure the operation of the over-current protection devices. (See Regulation 6.16.1.6). Control devices may be put into zone 3, according to the provisions in SANS 10142-1 (see Table 7.1, column four).

Quoting on the installation of heated towel rails

The registered person and the client should plan properly to keep within the requirements. It could be a very expensive exercise if the planning is not done thoroughly.

When quoting on the installation of heated towel rails, it is important to consider these factors that will influence the price:

Will the heated towel rails be fitted in:

  • a new installation where the construction is still in progress;
  • a half-completed installation with only the walls tiled and no bath, shower and basin installed; or
  • a fully completed installation with all the permanent accessories in place?

The first scenario is easy to deal with as the registered person carries out the periodic (general control) inspections on site and it is relatively easy to chase a wireway in the wall for the tubing and wiring. As mentioned before, the heated towel rail should have an isolator to enable future maintenance.

The isolator could also be installed next to the light switch – even in the same box – outside zones 0, 1, and 2. A switch will usually be on the outside of the bathroom. When the heated towel rail must be replaced or removed, this can be done easily, without breaking tiles and walls.

In the second scenario, it is more difficult for the accredited person and the cost of installing the appliance will be somewhat more as tiles will have to be removed and replaced. The accredited person should make sure that they know where the bath, shower and basin are going to be fitted. Remember that appliances should not be installed in zones 0, 1 and 2 in a bathroom.

In the third scenario, the placement of the heated towel rail should be planned and positioned carefully in accordance with Table 7.1 and the figurers on pages 190; 191; 192; and 193 of SANS 10142-1:2017 Wiring Code.

It is very important that the registered person stay up-to-date with new and amended regulations within SANS 10142-1: Low Voltage Installations.

Copies of SANS 10142-1 (Edition 2) are available from the ECA. Contact your nearest regional office for more information or to purchase the latest edition.

Chris Koen, ECA regional director, Highveld

 

Related Articles

  • Feedback: compulsory specification for GSL
  • Solar heated water to “become the norm” in SA
  • Position of new Eskom Group chief executive attracts interest
  • Compact pushbuttons, emergency stop buttons
  • Proud winner of a pallet jack